Congratulations, you've managed to annoy many people with animated avatars:
These animated .png avatars have certainly become more obvious over the past few days since the Stake.com bounty campaign started paying anyone for any old spam with no max post limit, even with animation_mode set to "once".
And the result is that theymos has now disable animated avatars for new entries:
OK, APNGs are now detected. Old ones are grandfathered for now, in part because people have ongoing campaigns, but in the future I might (or might not) go through and remove them.